1,2,4-benzotriazine oxides as radiosensitizers and selective cytotoxic agents

Abstract

A method of using 1,2,4-benzotriazine oxides, some of which are novel compounds, as radiosentitizers and selective cytotoxic agents is disclosed. These compounds are shown to specifically radiosensitize hypoxic tumor cells. Some are additionally disclosed to be useful as specific cytotoxic agents for these cells. They also show an unexpected ability to radiosensitize aerobic cells following or preceding a hypoxic incubation of the cells with the drug. This provides a basis for selective radiosensitization of tumors compared to normal cells. A novel method for preparing the 1,2,4- benzotriazine oxides is also disclosed.

We claim: 
     
       1. A method of radiosensitizing tumor cells of solid tumors having hypoxic cells, and susceptible to such treatment in a warm-blooded mammal, comprising: (a) administering to said mammal a pharmaceutical composition in an amount sufficient to produce radiosensitivity in said tumor cells, said pharmaceutical composition comprising a 1,2,4-benzotriazine oxide having the structure ##STR24## wherein X is H; hydrocarbyl (1-4C); hydrocarbyl (1-4C) substituted with OH, NH 2 , NHR or NRR; halogen; OH; alkoxy (1-4C); wherein the R groups are independently selected from alkyl (1-4C) and acyl (1-4C), optionally substituted with OH, NH 2 , alkyl (1-4C) secondary and dialkyl (1-4C) tertiary amino groups, alkoxy (1-4C) or halogen, and in the case of NRR, the two R's can be linked together directly or through a bridge oxygen into a morpholino ring, pyrrolidino ring or piperidino ring;   n is 0 or 1; and   Y 1  and Y 2  are independently either H; nitro, halogen; hydrocarbyl (1-14C) including cyclic and unsaturated hydrocarbyl, optionally substituted with 1 or 2 substituents selected from the group consisting of halogen, hydroxy, epoxy, alkoxy (1-4C), alkylthio (1-4C), primary amino (NH 2 ), lower alkyl (1-4C) secondary amino, dialkyl (1-4C) tertiary amino, dialkyl (1-4C) tertiary amino where the two alkyls are linked together to produce a morpholino, pyrrolidino or piperidino, acyloxy (1-4C), acylamido (1-4C) and thio analogs thereof, acetylaminoalkyl (1-4C), carboxy, alkoxycarbonyl (1-4C), carbamyl, alkylcarbamyl (1-4C), alkylsulfonyl (1-4C) or alkylphosphonyl (1-4C), wherein the hydrocarbyl can optionally be interrupted by a single ether (-O-) linkage; or wherein Y 1  and Y 2  are independently either morpholino, pyrrolidino, piperidino, NH 2 , NHR', NR'R' O(CO)R', NH(CO)R', O(SO)R', or O(POR')R' in which R' is a hydrocarbyl (1-4C) which may be substituted with OH, NH 2 , alkyl (1-4C) secondary amino, dialkyl (1-4C) tertiary amino, morpholino, pyrrolidino, piperidino, alkoxy (1-4C), or halogen substituents;   (b) subjecting said tumor cells to distinct radiation doses; and   (c) repeating steps (a) and (b) such that the mammal receives a plurality of doses of said pharmaceutical composition and radiation over an extended period of time, wherein each of said radiation doses is 1 to 5 Gy.   
     
     
       2. The method of claim 1, wherein step (a) is carried out prior to step (b). 
     
     
       3. The method of claim 1, wherein step (a) is carried out after step (b). 
     
     
       4. The method of claim 1, wherein each of said radiation doses is 2 to 2.5 Gy and said extended period of time is at least about 3 days or up to six weeks. 
     
     
       5. A method of treating a solid tumor having hypoxic cells and susceptible to such treatment, in a warm-blooded mammal, comprising the steps of (a) administering to such a warm-blooded mammal having such a tumor a pharmaceutical composition in an amount sufficient to produce cytotoxicity of the cells of said tumor, said pharmaceutical composition comprising a 1,2,4-benzotriazine oxide having the structure ##STR25## wherein X is H; hydrocarbyl (1-4C); n is 1; and   Y 1  and Y 2  are independently either H; nitro, halogen; hydrocarbyl (1-14C) including cyclic and unsaturated hydrocarbyl, optionally substituted with 1 or 2 substituents selected from the group consisting of halogen, hydroxy, epoxy, alkoxy (1-4C), alkylthio (1-4C), primary amino (NH 2 ), lower alkyl (1-4C) secondary amino, dialkyl (1-4C) tertiary amino, dialkyl (1-4C) tertiary amino where the two alkyls are linked together to produce a morpholino, pyrrolidino or piperidino, acyloxy (1-4C), acylamido (1-4C) and thio analogs thereof, acetylaminoalkyl (1-4C), carboxy, alkoxycarbonyl (1-4C), carbamyl, alkylcarbamyl (1-4C), alkylsulfonyl (1-4C) or alkylphosphonyl (1-4C), wherein the hydrocarbyl can optionally be interrupted by a single ether (-O-) linkage; or wherein Y 1  and Y 2  are independently either morpholino, pyrrolidino, piperidino, NH 2 , NHR', NR'R' O(CO)R', NH(CO)R', O(SO)R', or O(POR')R' in which R' is a hydrocarbyl (1-4C) which may be substituted with OH, NH 2 , alkyl (1-4C) secondary amino, dialkyl (1-4C) tertiary amino, morpholino, pyrrolidino, piperidino, alkoxy (1-4C), or halogen substituents;   (b) subjecting said tumor cells to distinct radiation doses; and   (c) repeating steps (a) and (b) such that the mammal receives a plurality of doses of drug and radiation over an extended period of time, wherein each of said radiation doses is 1 to 5 Gy.   
     
     
       6. The method of claim 5, wherein step (a) is carried out prior to step (b). 
     
     
       7. The method of claim 5, wherein step (a) is carried out after step (b). 
     
     
       8. The method of claim 5, wherein each of said radiation doses is 2 to 2.5 Gy, and said extended period of time is at least about 3 days or up to six weeks. 
     
     
       9. A method of radiosensitizing tumor cells of solid tumors having hypoxic cells, and susceptible to such treatment in a warm-blooded mammal, comprising: (a) administering to said mammal a pharmaceutical composition in an amount sufficient to produce radiosensitivity in said tumor cells, said pharmaceutical compositions comprising 3-hydroxy-1,2,4-benzotriazine 1,4-dioxide;   (b) subjecting said tumor cells to distinct radiation doses; and   (c) repeating steps (a) and (b) such that the mammal receives a plurality of doses of said pharmaceutical composition and radiation over an extended period of time, wherein each of said radiation doses is 1 to 5 Gy.